A screening apparatus for grading particulate material includes a grading screen having apertures for water and/or undersize particles to pass through. The grading screen is supported on a frame mounted on a chassis via resilient linkages, and the grading screen being vibrated by a vibrating device that imparts circular or reciprocating motion to the grading screen. The grading screen is set at a predetermined slope whereby material to be graded can be delivered onto an upper end while the grading screen is vibrated to convey the material over the grading screen and to cause undersize material to pass through the apertures. Oversize material is discharged from a lower end of the screen onto a conveyor or into a collection bay or hopper. A sump beneath the grading screen receives under-sized material passing through the grading screen, and a jet pump conveys material from the sump to a dewatering screen.